The role of SLRPs and large aggregating proteoglycans in collagen fibrillogenesis, extracellular matrix assembly, and mechanical function of fibrocartilage

ABSTRACT

Purpose

Proteoglycans, especially small leucine rich proteoglycans (SLRPs), play major roles in facilitating the development and regulation of collagen fibers and other extracellular matrix components. However, their roles in fibrocartilage have not been widely reviewed. Here, we discuss both SLRP and large aggregating proteoglycan’s roles in collagen fibrillogenesis and extracellular matrix assembly in fibrocartilage tissues such as the meniscus, annulus fibrosus (AF), and TMJ disc. We also discuss their expression levels throughout development, aging and degeneration, as well as repair.

Methods

A review of literature discussing proteoglycans and collagen fibrillogenesis in fibrocartilage was conducted and data from these manuscripts were analyzed and grouped to discuss trends throughout the tissue’s architectural zones and developmental stage.

Results

The spatial collagen architecture of these fibrocartilaginous tissues is reflected in the distribution of proteoglycans expressed, suggesting that each proteoglycan plays an important role in the type of architecture presented and associated mechanical function.

Conclusion

The unique structure-function relationship of fibrocartilage makes the varied architectures throughout the tissues imperative for their success and understanding the functions of these proteoglycans in developing and maintaining the fiber structure could inform future work in fibrocartilage replacement using tissue engineered constructs.

KEYWORDS:

• Meniscus
• annulus fibrosus
• intervertebral disc
• TMJ disc
• fibers

Acknowledgments

The authors would like to thank Dr. Jeffrey Ballyns, Dr. Stephen Sloan, and Mr. Jongkil Kim for his assistance in preparing histology. This work was supported by National Science Foundation grant CMMI 1927197 and a National Science Foundation Graduate Fellowship (DGE-1650441).

Disclosure statement

Dr. Bonassar is a co-founder of and holds equity in 3DBio Corp and is a consultant for Fidia Farmaceutici, SpA

Additional information

Funding

This work was supported by the National Science Foundation [CMMI 1927197]; National Science Foundation [DGE-1650441].